Yahoo and Bing said today that the two have begun testing integration between the two firms' systems, as part of the search alliance the firms announced about a year ago. According to the two, they expect to complete transition in the US and Canada over the next few months of their two systems. Bing and Yahoo linked in a search and advertising deal nearly a year ago, which calls for Bing to power Yahoo's search, and to direct Yahoo's advertisers to Microsoft's adCenter.